TABLE OF CONTENTS Most resins used as media for paints are solids or highly viscous materials, which have to be diluted with a liquid to lower their viscosity so that they can be manufactured into paint and the paints then applied to substrates.
The liquid can act as a true solvent for the resin, or as in the case of water can act as a diluent in water-based latex paints.
All solvents for paint resins are low molecular weight organic compounds, most of which can be classified as aliphatic or aromatic hydrocarbons and oxygenated organic compounds.
The most important property of a solvent is to dissolve the resin completely to give a clear solution that can be used to disperse the other ingredients of the paint formulation. The pigment dispersion is corrected for viscosity by further addition of solvent so that the paint can be applied. After application of the paint the solvent evaporates from the film to give a surface that is smooth, uniform, of the correct gloss, and free from imperfections ( cf. Chapter 4).
The role of solvents is very significant in that they control many factors associated with the properties of paint films. The physical and chemical characteristics of solvents that control paint properties are as follows.
A true solvent should dissolve a resin completely to give a clear solution over a wide range of concentrations, and, if the solution is applied as a film, the solvent should evaporate to give a transparent film...
